With the development of modern science and technology, ink jet printers with their reliable printing quality and low price are accepted by ordinary customers. In one type ink jet printer, an ink cartridge installation part of the printer is provided with a pressure detection device for detecting ink consumption in the ink cartridge and an electric contact part engaged with an electric contact in the ink cartridge, wherein the electric contact can move in a certain range.
U.S. Pat. Nos. 5,825,387, 6,364,472 and 6,793,329 have disclosed an ink cartridge for this type printer, and the ink cartridge is a container with elongated shape defined by opposite side walls and opposite end walls; the first feature is characterized by the model of the ink held in the ink container; and the second feature, different from the first one, is characterized by the ink color corresponding to the ink held in the ink container. The ink cartridge comprises an ink reservoir, a pump, a one-way valve, a fluid outlet and an electric contact surface part, wherein the ink reservoir is flexibly connected to a base plate and configured to receive ink, and forms fluid connection with a fluid inlet of the pump; the pump moves linearly and is provided with a variable volume chamber and integrated on the base plate, the ink is sucked from the ink reservoir through the fluid inlet of the pump when the bias pressure faces a volume expansion direction, and the ink is pressed out when the pump moves towards a volume shrinkage direction; the one-way valve is arranged at the inlet of the pump to allow the ink to flow out from the ink reservoir through the inlet of the pump and limit the ink to flow back to the ink reservoir; the fluid outlet is formed in the base plate; and the electric contact surface part is determined by a groove in a housing of the replaceable ink reservoir, and the groove is provided with a first inner surface serving as an engaging part and a second inner surface provided with a plurality of electric contacts, so that the electric contacts of the printer are engaged with the electric contacts of the ink cartridge without applying any pressure.
The complex pump structure adopted in the ink cartridge for supplying ink and being as an ink detection part comprises a plurality of elements such as a pump cap, the one-way valve, a spring and the like, and the physical properties and the mutual matching relationship of the elements increase many instable factors, for example, if the one-way valve at the inlet of the pump is not closed completely during ink supply, the ink flows back to the ink reservoir from the pump, so that the ink supply at the fluid outlet is insufficient and the print quality is influenced. Great difficulties are caused for the control of product quality, meanwhile, the manufacturing cost of the product is increased, and the detection mechanism is complex and low in precision.
In addition, the ink cartridges used in color ink jet printers generally include several ink cartridges filled with ink of different colors. In order to prevent assembly error of the ink cartridges, a corresponding identification characteristic is made on each model of the ink cartridges. However, when the problem of assembly error is solved, the production costs, comprising the manufacturing cost of moulds and the material control cost during the production process and the like, of the ink cartridge products are increased.